Over years, technique for manufacturing motor has been that: a specified number of stamp-forming steel sheets of stator core or rotor core are superposed together respectively to form a stator core or a rotor core according to design requirements, while the outer circumference and the inner bore of the stator core or the rotor core are not machined, thus the motor has bad accuracy and large tolerance, and when the motor is assembled, it is impossible to make a accurate adjustment upon its fit clearance, thus leading to a big fit error in coaxiality and cylindricity. Therefore more power loss and noise and other defects of the electrometer are different to remove. Even a motor with higher precision level is only lathed upon the outer circumference of its rotor core, and an improvement to the fit accuracy of the motor is limited.
In the conventional technique, generally four stamped ribs are provided at the relative position of the shaft with certain hardness, where a rotor core is assembled, or the shaft is embossed at the relative position where the rotor core is assembled, so as to enlarge the diameter of the shaft. For example, if the diameter of the shaft is 8 mm, the diameter of the position with stamped ribs or embossed patterns is 8.2 mm. In this way, when the shaft is inserted in the shaft bore of the rotor core, a tight fit may be achieved between the shaft and the shaft bore of the rotor core. However, a disadvantage of this processing technique is that when the motor has larger torsional force, it is easy to form a phenomenon that the rotor core rotates about the shaft while the shaft remains still, thus the durability of the motor are reduced.
Additionally, in the conventional technology, end caps of the motor are mostly fastened with on the stator core against end surfaces of the stator core, and the precision regarding the coaxiality of the bearing hole between the front-end and back-end caps is low, thus the running track of the rotor core is elliptical and the power is dissipated.
Therefore, although the conventional manufacturing technique enjoys easy machining and low cost, the products thereout can only meet general requirements and can be used only in general environments or locations.